The present invention relates generally to a catheter and more particularly to a bladder catheter. Generally, the invention relates to the type of catheter which is constructed to include a tube through which fluid pressure may be applied and a resilient hose which is usually invaginated into the interior of the tube and which is adapted to be exserted therefrom by the action of fluid pressure within the tube.
It has been previously proposed to line body cavities such as, for example, the urethra by means of a lining member which may be exserted or caused to protrude by application thereto of a pressure medium in order to enable introduction of instruments such as a catheter into a body cavity lined in this fashion, with the catheter being inserted subsequently or at the same time as the exsertion of the lining member. In this regard, reference is made, for example, to U.S. Pat. No. 3,589,356 and to German patent specification (Offenlegungsschrift) No. 2,011,634.
Catheters, which are introduced into the body in accordance with this principle, are particularly suited for use upon female patients when it is necessary to remove urine from the bladder and when medication in liquid form must be dispensed. An advantage arises in the use of such instruments in that sliding movement within the urethra is avoided thereby effectively avoiding the possibility of infective material present in the urethra becoming entrained into the bladder. This advantage arises due to the exsertion of the lining member or hose effected by the application of fluid pressure when the catheter is to be introduced into the bladder. As a result, the likelihood of bladder infection is reduced or eliminated.
However, it has been found that the practical application of the aforementioned type of catheterization may involve complications and may not be capable of performance without danger. Owing to the substantial friction which may occur between the hose which is being exserted and the tube of the instrument, there occurs a danger that the operator may lose his sense of feel for the restricted passages and curves in the urethra thereby giving rise to the possibility that injury may occur.
The present invention is intended to provide improvements over the previously proposed type of catheter wherein a flexible hose invaginated into a generally rigid tube may be exserted therefrom by the action of fluid pressure in such a manner that catheterization may be performed substantially without danger to a patient and in a substantially simpler manner while at the same time reducing the structural complexity of the device.